Holes and bores, particularly the inner faces of cylinders, such as the working cylinders of machines and motors, are honed in order to provide a specific surface quality and structure. It is ensured that the cross tracks exist such as are normally obtained with a simultaneous rotary and axial movement of the honing tools and they normally have a crossing angle between 30.degree. and 90.degree..
The honing cross tracks, which remain detectable in the surface structure, are intended to form "oil pockets", with the aim of permitting a better holding or retaining of lubricating oil on the cylinder surface so as to reduce wear. As a result of this honing, the service life of motors and machines and, in particular, internal combustion engines, can be significantly increased despite higher rotational speeds and piston speeds.
In addition, numerous coatings have been proposed with a view to improving the running and wear characteristics of piston rings. Thus, according to DE-OS 38 12 656 a composite nickel coating is plated on. DE-OS 35 02 143 proposes hardening by nitriding the outer coating in the case of a stainless steel ring. DE-OS 30 41 225 describes flame-spraying with a material comprising ferrochromium, as well as nickel-chromium-cobalt or molybdenum. Also according to DE-OS 30 17 907 a metal carbide and molybdenum are applied by flame-spraying. DE-OS 2841 722 proposes the application by plasma Jet of an oxide ceramic material, such as titanium dioxide or alumina. According to German utility model 18 82 791, an alumina is applied for improving the wear behavior and is covered by a soft running-in coating made from an unspecified material.
German utility model 19 53 020 proposes a coating formed from a porous, wear-resistant material, such as molybdenum or titanium by flame-spraying. According to Austrian patent 154 626, the piston ring material pores are to be filled with soft metal. In German patent 837 041, lead bronze is applied to a steel base material.
DE-OS 12 15 440 proposes a chromium coating with a running-in material formed from copper, zinc, bronze, or plastic inserted in grooves. DE-OS 38 13 617 uses copper, tin, or zinc on a chromium substrate.
In all of these cases, it was a question of obtaining an improved running-in behavior without reducing wear resistance.